Biomedical subjects

Ilmari Pyykkö

Publications and source records attributed to Ilmari Pyykkö.

27 records · Page 2Linked to original sources

PubMed2002

Protection and treatment of sensorineural hearing disorders caused by exogenous factors: experimental findings and potential clinical application.

During the last decade, there have been numerous interesting findings regarding the roles of neurotrophins, nitric oxide, reactive oxygen species, glutamate receptors, and shock protein in the auditory system. These findings have provided a scientific basis for the development of techniques to protect the auditory system against trauma as well as for the treatment of peripheral hearing disorders. This review focuses on recent advances in experimental prevention and treatment of hearing impairment which are expected to be of clinical value in the near future. Viral vector and non-viral vector gene therapy and transplantation of stem cells are discussed as potential treatments of irreversible sensorineural inner ear damage.

Animals↗

PubMed2002

Generating decision trees from otoneurological data with a variable grouping method.

When medical data sets are modelled by machine learning methods, wealth of variables may be available. This paper deals with variable selection for decision tree induction in the context of two otoneurological data sets: vertigo data, and postoperative nausea and vomiting data. First, a variable grouping method based on measures of association and graph theoretic techniques was used to gain insight into data. Then, representations of learning data were defined using the information from discovered variable groups, and decision trees were generated. The use of variable grouping method was beneficial by revealing interesting associations between variables and enabling generation of accurate and reasonable decision trees that modelled the application areas from different viewpoints.

Data Collection↗

PubMed2002

Use of electrocochleography for assessing endolymphatic hydrops in patients with Lyme disease and Ménière's disease.

From an otological standpoint, Lyme disease can manifest itself as Ménière's disease both clinically and electrophysiologically. The aim of this study was to describe the findings of routine clinical, auditory and vestibular tests in patients with Ménière's and Lyme disease and to use electrocochleography (ECoG) to assess the presence of endolymphatic hydrops (EH) in both diseases. Transtympanic ECoG was performed in 91 patients with Ménière's disease and in 11 patients with confirmed Lyme disease. In both diseases the majority of patients had more than one complaint. There was one case with isolated hearing loss in the Lyme disease group. Typical clinical manifestations of Ménière's disease (vertigo, sensorineural hearing loss and tinnitus) were found in 6/11 patients (54.5%) in the Lyme disease group. The ECoG results indicated that there were 65/91 patients (71.4%) with Ménière's disease and 5 patients (45.5%) with Lyme disease who presented with EH. No statistically significant difference was found between the incidence of different symptoms of Ménière's and Lyme disease. On the basis of these results, patients with Lyme disease should undergo careful examination and investigation, especially in endemic regions. The presence of EH does not exclude the presence of infection with borreliosis as a cause of Ménière's disease-like symptoms.

Adult↗

PubMed2002

Basic fibroblast growth factor in human saliva decreases with aging.

OBJECTIVE: Basic fibroblast growth factor (bFGF) has significant properties in wound healing and tissue repair and is suggested to be of importance for the maintenance of mucosal integrity in the upper digestive tract. The purpose of the present study was to identify any age-dependent variations in the concentration of bFGF in human saliva. STUDY DESIGN: Nonprospective, cross-sectional pilot study. METHODS: The study was based on findings from 182 healthy volunteers with ages ranging from 4 to 97 years. Mixed saliva samples were obtained by drooling. The saliva concentration of bFGF was determined with a commercially available enzyme-linked immunosorbent assay kit. RESULTS: The mean saliva concentration of bFGF was 0.41 pg/mL with no gender differences. In persons aged 4 to 19 years, the mean concentration was 0.72 pg/mL; in those aged 20 to 65 years, 0.33 pg/mL; and in those aged 66 to 97 years, 0.005 pg/mL. These age-dependent differences were highly significant. In the youngest group the saliva concentration of bFGF varied more than in the other groups. CONCLUSIONS: The saliva concentration of bFGF varies with individual age, with the highest levels among young individuals, even levels during a mature phase of life, and low levels toward the end of the life cycle. This strongly suggests a physiological implication of bFGF in saliva.

Adolescent↗

PubMed2002

Is hearing preservation useful in vestibular schwannoma surgery?

The goal of our study was to examine the usefulness of preserved hearing after unilateral vestibular schwannoma removal. The patients were assessed by clinical evaluation, preoperative and postoperative audiometric evaluation, operative findings, and postoperative functional results. Hearing was preserved in 47 of 119 patients. The postoperative hearing was better than 30 dB in 10 patients. During the follow-up, the hearing decreased 5 dB on average, and almost all of the decrement occurred during the first 6 months. Subjectively, the preserved hearing assisted in understanding of speech in 62% of the patients. Tinnitus did not interfere with understanding of speech. The age of the patients was the most significant factor associated with preserved hearing. Sixty-six percent of the patients with hearing preservation rated their preserved hearing as valuable. Neither tinnitus nor speech distortion reduced the appreciation for hearing preservation. We conclude that efforts to preserve hearing are worthwhile.

Audiometry↗

PubMed2002

Nearest neighbour classification of otoneurological data.

We studied the nearest neighbour classification of patient cases with benign positional vertigo, Meniere's disease, sudden deafness, traumatic vertigo, vestibular neuritis, and vestibular schwannoma. The classification results were compared to the inference results obtained by an otoneurological expert system ONE whose inference mechanism somewhat resembles the classical nearest neighbour method. With respect to the predictive accuracy, the classification results of these two systems agreed. The best predictive accuracy for the expert system ONE was 79.7% and for the nearest neighbour method 80.5%. However, differences in the true positive rates for sudden deafness, traumatic vertigo, vestibular neuritis, and vestibular schwannoma were found. The nearest neighbour classification results will be used in the refinement of ONE's knowledge base.

Data Collection↗

PubMed2000

Individual Risk Factors in the Development of Noise-Induced Hearing Loss.

We have analysed the association of noise-induced hearing loss with various risk factors among 685 workers in forest, shipyard, and paper mills. Occupational histories, health, environmental factors, and noise exposures of each worker were retrieved from the database of NoiseScan, our expert program on hearing. The mean hearing level at 4 kHz was 21.5 dB +/- 20.3 dB HL. It correlated significantly with age, noise emission level and noise exposure level. However, these factors could only explain about 2 dB HL of the variation in hearing level. Impulse noise in the shipyard work caused increase in hearing level of 12 dB HL at 4 kHz when compared to steady state noise exposure of forest work. Hearing level correlated with serum cholesterol levels, use of analgesics, blood pressure and smoking. An elevated cholesterol level increased hearing loss in both the high- and low-exposure groups. The use of analgesics did not increase a permanent threshold shift in the low-exposure group, but did in the high-exposure group. Systolic blood pressure, smoking, cholesterol level and the use of painkillers explained 36 % of the variation in hearing level at 4 kHz, whereas noise exposure alone explained 25 % of the corresponding variation.

Journal Article↗

PubMedDate not supplied

Lyme borreliosis and facial paralysis--a prospective analysis of risk factors and outcome.

PURPOSE: To evaluate the incidence of Lyme borreliosis in patients with acute idiopathic facial paralysis with special emphasis on the risk factors that explain the poor outcome of facial paralysis and occurrence of Lyme borreliosis. MATERIALS AND METHODS: During a 2-year period, we prospectively studied 503 consecutive patients with acute idiopathic facial paralysis for the presence of Lyme borreliosis. We screened the patients for antibodies to Borrelia burgdorferi and for symptoms or signs related to Lyme borreliosis. Chi-square and logistic regression tests were used for the statistical analysis. Special attention was paid to strict criteria for the diagnosis of Lyme borreliosis. RESULTS: Eleven (2.2%) of the 503 patients with facial paralysis had Lyme borreliosis. Fever, headache, pharyngalgia, enlarged cervical lymph nodes, bilateral paralysis, and arthralgia were more common in patients with Lyme borreliosis than in those without it. In the logistic regression modeling the best combination of explanatory variables for predicting the occurrence of Lyme borreliosis included summer season at the onset of facial paralysis, presence of enlarged cervical lymph nodes, and arthralgia. The best combination of explanatory variables to predict the poor outcome of facial paralysis was total paralysis of facial nerves, recurrent facial paralysis, and hyperacusis. CONCLUSIONS: Lyme borreliosis is an important infectious cause of facial paralysis. In our study, 11 of 503 patients with acute idiopathic facial paralysis had Lyme borreliosis. The screening for serum antibodies in addition to the thorough evaluation of the history of the patient and of the patient's clinical signs or symptoms possibly linked with Lyme borreliosis, are essential when diagnosing Lyme borreliosis.

Acute Disease↗

PubMedDate not supplied

Comparison of the protective efficacy of neurotrophins and antioxidants for vibration-induced trauma.

BACKGROUND: Patients undergoing temporal bone surgery or subjects working with vibrating tools may develop vibration-induced hearing loss (VHL). The aim of this study was to characterize the effects of pretreatment with N-acetylcysteine (NAC) or the neurotrophic factors, brain-derived neurotrophic factor (BDNF) and ciliary neurotrophic factor (CNTF), on VHL in an animal model. METHODS: Trauma to the cochlea was created with a vibrating probe placed on the bone of the external ear canal. BDNF and CNTF(Ax1) were delivered into the cochlea with mini-osmotic pumps. NAC was delivered into the cochlea by round window membrane (RWM) injection, by RWM permeation, or by oral administration. Hearing was evaluated with electrocochleography (ECoG). RESULTS: For control animals, vibration resulted in an average immediate threshold shift of 42 +/- 26 dB. NAC provided no protective benefit in animals subjected to VHL, regardless of the delivery method, with average threshold shifts varying from 38 to 56 dB across groups. NAC injection through the round window membrane was toxic, causing a ECoG threshold shift of >25 dB. In BDNF+CNTF(Ax1)-treated animals, immediate hearing loss was similar to that in control animals. There was a trend of threshold recovery by 1 day after vibration; however, the improvement was not statistically significant, nor was there a significant difference in 1-day thresholds across groups. CONCLUSIONS: Local infusion of BDNF and CNTF(Ax1) may enhance the rate of recovery from VHL, compared to control animals. In contrast, NAC had no effect on VHL, and when delivered by RWM injection, was actually toxic to the inner ear.

Animals↗